Question

what is work? when is it said to be done​

Answer 1

$\huge\underline\mathfrak{Work:-}$

Work is said to be done when an applied force produces a displacement in the body in its own direction.

So, Work = Force $\times$ Displacement $\times$ cos$\theta$

• It is a scaler quantity.

• It's SI unit is Joule (J).

• CGS unit is erg.

1J = ${10^7}$ energy.

I KJ = 10³ J

$\huge\underline\mathfrak{1\:Joule:-}$

Work is done is one Joule if 1 N displaces a body by 1M in its own direction.

• Work is said to be done when:

(i) a moving object comes to rest.

(ii) an object at rest starts moving.

(iii) velocity of an object changes.

(iv) shape of an object changes.